Chapter 7 glossary Flashcards
amino acids
building blocks of protein; link together end to end by peptide bonds to form the polypeptide chains that compromise proteins
anagen phase
aka growth phase; hair phase during which new hair is produced
catagen phase
brief transition period between the growth and resting phases of a hair follicle; signals the end of the growth phase
COHNS elements
5 elements; carbon, oxygen, hydrogen, nitrogen, and sulfur that makeup human hair, skin, tissue, and nails
cortex
fibrous protein layer of the hair; responsible for the strength, elasticity, and color of hair
cowlick
hair that grows straight up or at a different angle than the other hair; usually more noticeable at the crown
cysteine
amino acid with a sulfur atom that joins together two peptide strands
dermal papilla
cone-shaped elevation found at the base of the hair bulb
disulfide bond
strong chemical side bond that joins the sulfur atoms of two neighboring cysteine amino acids to create one cysteine, which joins together two polypeptide strands like rungs on a ladder
eumelanin
consists of brown and black pigment and is the predominant pigment in black and brunette hair
hair bulb
found at the base of the follicle; has a bulb shape and contains living cells that will form the hair strand
hair cuticle
outermost layer of hair; formed from cells that resemble form singles on a roof; protects the cortex
hair density
measures the number of individual hair strands on 1 square in. of scalp
hair elasticity
ability of the hair to stretch and return to its original length without breaking
hair follicle
tube like structure in the skin or scalp that surrounds the hair root and anchors the hair in the skin
hair porosity
refers to ability of the hair to absorb moisture
hair root
part of the hair located below the surface of the epidermis
hair shaft
part of the hair that projects above the epidermis
hair stream
hair flowing in same direction;; from follicles sloping in the same direction
hair texture
thickness/diameter of an individual hair strand
hydrogen bond
weak physical cross-link side bond that is easily broken by water or heat
keratinization
process by which newly formed cells in hair bulbs mature, fill with keratin, move upward, lose their nucleus and die
lanthionine bond
created when disulfide bonds are broken by hydroxide chemical hair relaxers and lose a sulfur molecule
lanugo hair
short, fine hair that covers a fetus and sheds within a few weeks of birth
medulla
innermost layer found in coarse hair; aka pith or core; absent in fine hair
melanin
tiny grains of pigment in the cortex that give natural color to the hair
peptide bonds
aka end bond; chemical bond that joins amino acids to each other, end to end to form a polypeptide chain
pheomelanin
yellow to red pigment found in natural blonde to red shades of hair
polypeptide chain
long chain of amino acids linked by peptide bonds
salt bonds
weak physical cross-link side bond between adjacent polypeptide chains that is broken by changes in pH
side bonds
bonds that cross link polypeptide chains and are responsible for the extreme strength and elasticity of human hair; account for one third of hair’s overall strength
telogen phase
aka resting phase in the hair cycle that lasts until the fully grown hair is shed
terminal hair
long, coarse, pigmented hair found on scalp, legs, arms, and body
trichology
scientific study of hair and its diseases and care
vellus hair
short, fine, unpigmented hair on the body; aka peach fuzz; less than one third inches long and can appear anywhere on skin except palms, soles of feet, and lips
wave pattern
amount of movement or shape of the hair strand; described as straight wavy, curly, or coily
whorl
occurs when hair leaves the follicles at an angle; air grows in a circular pattern on the crown of the head
